// Copyright 2020 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package dashboard

import (
	"net/http"
	"sync/atomic"

	"github.com/pingcap-incubator/tidb-dashboard/pkg/apiserver"
)

// Redirector is used to redirect when the dashboard is started in another PD.
type Redirector struct {
	address atomic.Value
}

// NewRedirector creates a new Redirector.
func NewRedirector() *Redirector {
	h := new(Redirector)
	h.address.Store("")
	return h
}

// SetAddress is used to set a new address to be redirected.
func (h *Redirector) SetAddress(addr string) {
	h.address.Store(addr)
}

// ServeHTTP implements http.Handler.
func (h *Redirector) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	addr := h.address.Load().(string)
	if addr == "" {
		apiserver.StoppedHandler.ServeHTTP(w, r)
		return
	}
	http.Redirect(w, r, addr+r.RequestURI, http.StatusTemporaryRedirect)
}
